Physical disability in older age has become a critical clinical and public health concern due to its high associated health care costs and the rapidly growing number of older adults. The prevalence of disability has increased over the past 2 decades, in spite of earlier progress. Thus, age-related disability remains a substantial public health burden. Exposures to environmental toxins are potential modifiable risk factors that have received little attention. In particular, exposure to air pollution is associated with elevated riss of conditions, cardiovascular and respiratory disease, that are primary causes of disability. And health effects of air pollution appear to be magnified in older adults. Yet studies of single syste endpoints do not reflect the effects of air pollution exposure on multiple organ systems, even though co-morbid conditions, clinical and subclinical, are common in older adults. The direct relation of air pollution to disability among older adults remains virtually unexplored. Data indicating an association between air pollution and age-related disability would be critical for setting environmental policy, which could reduce the burden of disability in the population. We propose to conduct an exploratory epidemiologic study of air pollution exposure, specifically, exposure to traffic-related air pollution in relation to disability in older adults. This study, a collaboration of aging and environmental health disciplines, will capitalize on existing data from the Chicago health and Aging Project (CHAP), a study of over 10,000 adults, ages 65+, who live on the south side of Chicago, IL. CHAP enrolled its first participants in 1993. Participants have triennial in-home study visits, which include disability assessments. We will estimate exposures to traffic-related air pollution by estimating participants' residential distance to nearest busy rad (DTR; incl. highways, truck routes and bus routes, along with the traffic count data) and exposure to oxides of nitrogen (NOx), a major component of vehicle emissions. In CHAP, DTR will gauge long-term exposure, because the area's roads and bus routes have been in place for decades, and most participants have lived at the same address for many years. Estimated NOx exposures are potentially more spatiotemporally precise and extend back to 1999. We will use all of this data to evaluate whether exposure to traffic-generated air pollution is related to incident disability and disability progression. This exploratory project combines two features that are presently not available in any other large cohort study of air pollution and late-life health. 1) The residentially stable population comprises older whites and blacks with detailed longitudinal data on disability. (2) The urban study area not only has had stable road and traffic patterns over time, but also lies within a region where detailed NOx measurements have been taking place. This project will generate important evidence on the plausibility of a relation between air pollution exposure and disability, stimulating further work to confirm and elaborate any associations found.